1. Technical Field
The invention relates to vehicle brake systems and more particularly to a pilot master cylinder for the brake system which is positionable inside the vehicle cab.
2. Description of the Problem
Front engine busses pose a number of problems for engine and vehicle system layout not inherent in conventional or rear engine configurations. Front engine busses have a characteristic flat front or “snub nose” appearance, with the bus driver and engine positioned over the front wheels. The front dash panel is spaced from the front wall of the vehicle by only a few inches. Access to the engine is from the passenger compartment or through relatively small panels in the sides or front of the vehicle. The engine compartment is much smaller than in conventional engine vehicles and components that are located in the engine compartment of conventional engine vehicles, such as brake master cylinders, must frequently be relocated due to size considerations and to considerations relating to providing linkages between operator controls, such as between a brake pedal and the brake master cylinder. For example, in a conventional engine bus a standard horizontally inclined master cylinder may be used where in a front engine bus the master cylinder has frequently had to be relocated due to lack of under hood clearance. On front engine vehicles the brake master cylinder has commonly been located on the vehicle frame, where it is exposed to road splash which poses a corrosion threat.
Recent developments in vehicle design favor the use of full power brake systems where the brake master cylinder, rather than providing the required pressure for actuating the brakes, provides a hydraulic pilot signal to an electronic controller, which in turn generates the signals for actuation, modulation and release of the individual wheel end brakes for normal braking, anti-lock braking, stability control and traction control. It would be advantageous to exploit the elimination of the need for power boost to configure a pilot master cylinder which could be repositioned off the frame of the vehicle, preferably to inside the passenger compartment or the under hood compartment to avoid corrosion exposure and improve accessibility.